NGT orders urgent action to curb sewage pollution in Korattur, Madambakkam lakes

The southern bench of the National Green Tribunal (NGT) has directed authorities to take urgent measures to stop untreated sewage from entering Korattur and Madambakkam lakes, observing that domestic sewage remains the primary cause of pollution and ecological degradation in both waterbodies.

In separate orders issued on June 9, the tribunal directed the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB), Tambaram City Municipal Corporation, Water Resources Department (WRD), and other agencies to plug sewage outfalls, strengthen sewerage infrastructure, restore lake ecosystems, and remove encroachments.

In the Korattur lake case, which was filed by the Korattur Aeri Paadhukaappu Makkal Iyakkam, the Tribunal found that untreated sewage from unsewered and inadequately sewered residential areas in and around Greater Chennai Corporation’s Zone VII continued to enter the lake.

Water quality analyses revealed elevated levels of contaminants, pointing to persistent sewage pollution. The bench directed the CMWSSB to identify and close illegal sewer connections and discharge points entering the lake within six months.

It also ordered the District Collector, WRD, and Greater Chennai Corporation (GCC) to survey lake boundaries and bund areas to identify and remove encroachments and directed the GCC and WRD to undertake ecological restoration measures, including removal of water hyacinth.

While the case was filed over allegations of both sewage and industrial pollution, the tribunal noted that recent inspections by the Tamil Nadu Pollution Control Board (TNPCB) found no evidence of industrial effluent discharge into the lake. It observed that industrial units in the Ambattur Industrial Estate had largely complied with pollution-control norms. 

The Tribunal also noted that the TNPCB had imposed environmental compensation of ₹5.10 crore on Aavin for earlier effluent-management violations, and that the dairy had since upgraded its effluent treatment plant.

‘Expedite UGSS’

In the Madambakkam lake case, initiated suo motu by the Tribunal, the bench directed the Tambaram City Municipal Corporation to expedite implementation of the Underground Sewerage Scheme (UGSS) and immediately prevent untreated sewage from entering the lake.

Water quality tests showed faecal coliform and total coliform levels exceeding permissible limits, rendering the water unfit for drinking and other designated uses. The Tribunal directed the corporation to operationalise interception and diversion systems and decentralised sewage treatment plants pending completion of the UGSS, permanently plug sewage outfalls entering the lake, and ensure proper collection and treatment of wastewater. It also instructed the TNPCB to undertake periodic monitoring and initiate action against violations.

The WRD has been directed to undertake restoration works, including desilting, removal of aquatic weeds and strengthening of lake bunds, while the Chennai Metropolitan Development Authority (CMDA) has been tasked to ensure compliance with environmental safeguards in future developments around the lake.